Scientists and mission controllers are currently viewing never-before-seen images of Hartley 2 appearing on their computer terminal screens.

Comet Hartley 2 can be seen in glorious detail in this image from NASA's EPOXI mission. It was taken as the spacecraft flew by around 6:59 a.m. PDT (9:59 a.m. EDT), from a distance of about 700 kilometers (435 miles). Jets can be seen streaming out of the nucleus. Image credit: NASA/JPL-Caltech/UMD

This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument. Image credit: NASA/JPL-Caltech/UMD

This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument. Image credit: NASA/JPL-Caltech/UMD

“The mission team and scientists have worked hard for this day,” said Tim Larson, EPOXI project manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “It’s good to see Hartley 2 up close.”

This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument. Image credit: NASA/JPL-Caltech/UMD

This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument. Image credit: NASA/JPL-Caltech/UMD

This is one of the first images sent back to Earth from the NASA's EPOXI mission after it flew by comet Hartley 2 around 7 a.m. PDT (10 a.m. EDT) on Nov. 4, 2010.

Mission navigators are working to determine the spacecraft’s closest approach distance. Preliminary estimates place the spacecraft close to the planned-for 700 kilometers (435 miles). Eight minutes after closest approach, at 6:59:47 a.m. PDT ( 9:59:47 a.m. EDT), the spacecraft’s high-gain antenna was pointed at Earth and began downlinking vital spacecraft health and other engineering data stored aboard the spacecraft’s onboard computer during the encounter. About 20 minutes later, the first images of the encounter made the 37-million-kilometer (23-million-mile) trip from the spacecraft to NASA’s Deep Space Network antennas in Goldstone, Calif., appearing moments later on the mission’s computer screens.

“We are all holding our breath to see what discoveries await us in the observations near closest approach,” said EPOXI principal investigator Michael A’Hearn of the University of Maryland, College Park.

A post-encounter news conference will be held at 1 p.m. PDT (4 p.m. EDT) in the von Karman auditorium at JPL. It will be carried live on NASA TV.

EPOXI is an extended mission that utilizes the already “in-flight” Deep Impact spacecraft to explore distinct celestial targets of opportunity. The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). The spacecraft has retained the name “Deep Impact.”

JPL manages the EPOXI mission for NASA’s Science Mission Directorate, Washington. The University of Maryland is home to the mission’s principal investigator, Michael A’Hearn. Drake Deming of NASA’s Goddard Space Flight Center, Greenbelt, Md., is the science lead for the mission’s extrasolar planet observations. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.